1 // shared_ptr and weak_ptr implementation details -*- C++ -*- 2 3 // Copyright (C) 2007-2016 Free Software Foundation, Inc. 4 // 5 // This file is part of the GNU ISO C++ Library. This library is free 6 // software; you can redistribute it and/or modify it under the 7 // terms of the GNU General Public License as published by the 8 // Free Software Foundation; either version 3, or (at your option) 9 // any later version. 10 11 // This library is distributed in the hope that it will be useful, 12 // but WITHOUT ANY WARRANTY; without even the implied warranty of 13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 // GNU General Public License for more details. 15 16 // Under Section 7 of GPL version 3, you are granted additional 17 // permissions described in the GCC Runtime Library Exception, version 18 // 3.1, as published by the Free Software Foundation. 19 20 // You should have received a copy of the GNU General Public License and 21 // a copy of the GCC Runtime Library Exception along with this program; 22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 23 // <http://www.gnu.org/licenses/>. 24 25 // GCC Note: Based on files from version 1.32.0 of the Boost library. 26 27 // shared_count.hpp 28 // Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd. 29 30 // shared_ptr.hpp 31 // Copyright (C) 1998, 1999 Greg Colvin and Beman Dawes. 32 // Copyright (C) 2001, 2002, 2003 Peter Dimov 33 34 // weak_ptr.hpp 35 // Copyright (C) 2001, 2002, 2003 Peter Dimov 36 37 // enable_shared_from_this.hpp 38 // Copyright (C) 2002 Peter Dimov 39 40 // Distributed under the Boost Software License, Version 1.0. (See 41 // accompanying file LICENSE_1_0.txt or copy at 42 // http://www.boost.org/LICENSE_1_0.txt) 43 44 /** @file bits/shared_ptr_base.h 45 * This is an internal header file, included by other library headers. 46 * Do not attempt to use it directly. @headername{memory} 47 */ 48 49 #ifndef _SHARED_PTR_BASE_H 50 #define _SHARED_PTR_BASE_H 1 51 52 #include <typeinfo> 53 #include <bits/allocated_ptr.h> 54 #include <ext/aligned_buffer.h> 55 56 namespace std _GLIBCXX_VISIBILITY(default) 57 { 58 _GLIBCXX_BEGIN_NAMESPACE_VERSION 59 60 #if _GLIBCXX_USE_DEPRECATED 61 template<typename> class auto_ptr; 62 #endif 63 64 /** 65 * @brief Exception possibly thrown by @c shared_ptr. 66 * @ingroup exceptions 67 */ 68 class bad_weak_ptr : public std::exception 69 { 70 public: 71 virtual char const* what() const noexcept; 72 73 virtual ~bad_weak_ptr() noexcept; 74 }; 75 76 // Substitute for bad_weak_ptr object in the case of -fno-exceptions. 77 inline void 78 __throw_bad_weak_ptr() 79 { _GLIBCXX_THROW_OR_ABORT(bad_weak_ptr()); } 80 81 using __gnu_cxx::_Lock_policy; 82 using __gnu_cxx::__default_lock_policy; 83 using __gnu_cxx::_S_single; 84 using __gnu_cxx::_S_mutex; 85 using __gnu_cxx::_S_atomic; 86 87 // Empty helper class except when the template argument is _S_mutex. 88 template<_Lock_policy _Lp> 89 class _Mutex_base 90 { 91 protected: 92 // The atomic policy uses fully-fenced builtins, single doesn't care. 93 enum { _S_need_barriers = 0 }; 94 }; 95 96 template<> 97 class _Mutex_base<_S_mutex> 98 : public __gnu_cxx::__mutex 99 { 100 protected: 101 // This policy is used when atomic builtins are not available. 102 // The replacement atomic operations might not have the necessary 103 // memory barriers. 104 enum { _S_need_barriers = 1 }; 105 }; 106 107 template<_Lock_policy _Lp = __default_lock_policy> 108 class _Sp_counted_base 109 : public _Mutex_base<_Lp> 110 { 111 public: 112 _Sp_counted_base() noexcept 113 : _M_use_count(1), _M_weak_count(1) { } 114 115 virtual 116 ~_Sp_counted_base() noexcept 117 { } 118 119 // Called when _M_use_count drops to zero, to release the resources 120 // managed by *this. 121 virtual void 122 _M_dispose() noexcept = 0; 123 124 // Called when _M_weak_count drops to zero. 125 virtual void 126 _M_destroy() noexcept 127 { delete this; } 128 129 virtual void* 130 _M_get_deleter(const std::type_info&) noexcept = 0; 131 132 void 133 _M_add_ref_copy() 134 { __gnu_cxx::__atomic_add_dispatch(&_M_use_count, 1); } 135 136 void 137 _M_add_ref_lock(); 138 139 bool 140 _M_add_ref_lock_nothrow(); 141 142 void 143 _M_release() noexcept 144 { 145 // Be race-detector-friendly. For more info see bits/c++config. 146 _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_use_count); 147 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_use_count, -1) == 1) 148 { 149 _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_use_count); 150 _M_dispose(); 151 // There must be a memory barrier between dispose() and destroy() 152 // to ensure that the effects of dispose() are observed in the 153 // thread that runs destroy(). 154 // See http://gcc.gnu.org/ml/libstdc++/2005-11/msg00136.html 155 if (_Mutex_base<_Lp>::_S_need_barriers) 156 { 157 __atomic_thread_fence (__ATOMIC_ACQ_REL); 158 } 159 160 // Be race-detector-friendly. For more info see bits/c++config. 161 _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_weak_count); 162 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_weak_count, 163 -1) == 1) 164 { 165 _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_weak_count); 166 _M_destroy(); 167 } 168 } 169 } 170 171 void 172 _M_weak_add_ref() noexcept 173 { __gnu_cxx::__atomic_add_dispatch(&_M_weak_count, 1); } 174 175 void 176 _M_weak_release() noexcept 177 { 178 // Be race-detector-friendly. For more info see bits/c++config. 179 _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_weak_count); 180 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_weak_count, -1) == 1) 181 { 182 _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_weak_count); 183 if (_Mutex_base<_Lp>::_S_need_barriers) 184 { 185 // See _M_release(), 186 // destroy() must observe results of dispose() 187 __atomic_thread_fence (__ATOMIC_ACQ_REL); 188 } 189 _M_destroy(); 190 } 191 } 192 193 long 194 _M_get_use_count() const noexcept 195 { 196 // No memory barrier is used here so there is no synchronization 197 // with other threads. 198 return __atomic_load_n(&_M_use_count, __ATOMIC_RELAXED); 199 } 200 201 private: 202 _Sp_counted_base(_Sp_counted_base const&) = delete; 203 _Sp_counted_base& operator=(_Sp_counted_base const&) = delete; 204 205 _Atomic_word _M_use_count; // #shared 206 _Atomic_word _M_weak_count; // #weak + (#shared != 0) 207 }; 208 209 template<> 210 inline void 211 _Sp_counted_base<_S_single>:: 212 _M_add_ref_lock() 213 { 214 if (_M_use_count == 0) 215 __throw_bad_weak_ptr(); 216 ++_M_use_count; 217 } 218 219 template<> 220 inline void 221 _Sp_counted_base<_S_mutex>:: 222 _M_add_ref_lock() 223 { 224 __gnu_cxx::__scoped_lock sentry(*this); 225 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_use_count, 1) == 0) 226 { 227 _M_use_count = 0; 228 __throw_bad_weak_ptr(); 229 } 230 } 231 232 template<> 233 inline void 234 _Sp_counted_base<_S_atomic>:: 235 _M_add_ref_lock() 236 { 237 // Perform lock-free add-if-not-zero operation. 238 _Atomic_word __count = _M_get_use_count(); 239 do 240 { 241 if (__count == 0) 242 __throw_bad_weak_ptr(); 243 // Replace the current counter value with the old value + 1, as 244 // long as it's not changed meanwhile. 245 } 246 while (!__atomic_compare_exchange_n(&_M_use_count, &__count, __count + 1, 247 true, __ATOMIC_ACQ_REL, 248 __ATOMIC_RELAXED)); 249 } 250 251 template<> 252 inline bool 253 _Sp_counted_base<_S_single>:: 254 _M_add_ref_lock_nothrow() 255 { 256 if (_M_use_count == 0) 257 return false; 258 ++_M_use_count; 259 return true; 260 } 261 262 template<> 263 inline bool 264 _Sp_counted_base<_S_mutex>:: 265 _M_add_ref_lock_nothrow() 266 { 267 __gnu_cxx::__scoped_lock sentry(*this); 268 if (__gnu_cxx::__exchange_and_add_dispatch(&_M_use_count, 1) == 0) 269 { 270 _M_use_count = 0; 271 return false; 272 } 273 return true; 274 } 275 276 template<> 277 inline bool 278 _Sp_counted_base<_S_atomic>:: 279 _M_add_ref_lock_nothrow() 280 { 281 // Perform lock-free add-if-not-zero operation. 282 _Atomic_word __count = _M_get_use_count(); 283 do 284 { 285 if (__count == 0) 286 return false; 287 // Replace the current counter value with the old value + 1, as 288 // long as it's not changed meanwhile. 289 } 290 while (!__atomic_compare_exchange_n(&_M_use_count, &__count, __count + 1, 291 true, __ATOMIC_ACQ_REL, 292 __ATOMIC_RELAXED)); 293 return true; 294 } 295 296 template<> 297 inline void 298 _Sp_counted_base<_S_single>::_M_add_ref_copy() 299 { ++_M_use_count; } 300 301 template<> 302 inline void 303 _Sp_counted_base<_S_single>::_M_release() noexcept 304 { 305 if (--_M_use_count == 0) 306 { 307 _M_dispose(); 308 if (--_M_weak_count == 0) 309 _M_destroy(); 310 } 311 } 312 313 template<> 314 inline void 315 _Sp_counted_base<_S_single>::_M_weak_add_ref() noexcept 316 { ++_M_weak_count; } 317 318 template<> 319 inline void 320 _Sp_counted_base<_S_single>::_M_weak_release() noexcept 321 { 322 if (--_M_weak_count == 0) 323 _M_destroy(); 324 } 325 326 template<> 327 inline long 328 _Sp_counted_base<_S_single>::_M_get_use_count() const noexcept 329 { return _M_use_count; } 330 331 332 // Forward declarations. 333 template<typename _Tp, _Lock_policy _Lp = __default_lock_policy> 334 class __shared_ptr; 335 336 template<typename _Tp, _Lock_policy _Lp = __default_lock_policy> 337 class __weak_ptr; 338 339 template<typename _Tp, _Lock_policy _Lp = __default_lock_policy> 340 class __enable_shared_from_this; 341 342 template<typename _Tp> 343 class shared_ptr; 344 345 template<typename _Tp> 346 class weak_ptr; 347 348 template<typename _Tp> 349 struct owner_less; 350 351 template<typename _Tp> 352 class enable_shared_from_this; 353 354 template<_Lock_policy _Lp = __default_lock_policy> 355 class __weak_count; 356 357 template<_Lock_policy _Lp = __default_lock_policy> 358 class __shared_count; 359 360 361 // Counted ptr with no deleter or allocator support 362 template<typename _Ptr, _Lock_policy _Lp> 363 class _Sp_counted_ptr final : public _Sp_counted_base<_Lp> 364 { 365 public: 366 explicit 367 _Sp_counted_ptr(_Ptr __p) noexcept 368 : _M_ptr(__p) { } 369 370 virtual void 371 _M_dispose() noexcept 372 { delete _M_ptr; } 373 374 virtual void 375 _M_destroy() noexcept 376 { delete this; } 377 378 virtual void* 379 _M_get_deleter(const std::type_info&) noexcept 380 { return nullptr; } 381 382 _Sp_counted_ptr(const _Sp_counted_ptr&) = delete; 383 _Sp_counted_ptr& operator=(const _Sp_counted_ptr&) = delete; 384 385 private: 386 _Ptr _M_ptr; 387 }; 388 389 template<> 390 inline void 391 _Sp_counted_ptr<nullptr_t, _S_single>::_M_dispose() noexcept { } 392 393 template<> 394 inline void 395 _Sp_counted_ptr<nullptr_t, _S_mutex>::_M_dispose() noexcept { } 396 397 template<> 398 inline void 399 _Sp_counted_ptr<nullptr_t, _S_atomic>::_M_dispose() noexcept { } 400 401 template<int _Nm, typename _Tp, 402 bool __use_ebo = !__is_final(_Tp) && __is_empty(_Tp)> 403 struct _Sp_ebo_helper; 404 405 /// Specialization using EBO. 406 template<int _Nm, typename _Tp> 407 struct _Sp_ebo_helper<_Nm, _Tp, true> : private _Tp 408 { 409 explicit _Sp_ebo_helper(const _Tp& __tp) : _Tp(__tp) { } 410 411 static _Tp& 412 _S_get(_Sp_ebo_helper& __eboh) { return static_cast<_Tp&>(__eboh); } 413 }; 414 415 /// Specialization not using EBO. 416 template<int _Nm, typename _Tp> 417 struct _Sp_ebo_helper<_Nm, _Tp, false> 418 { 419 explicit _Sp_ebo_helper(const _Tp& __tp) : _M_tp(__tp) { } 420 421 static _Tp& 422 _S_get(_Sp_ebo_helper& __eboh) 423 { return __eboh._M_tp; } 424 425 private: 426 _Tp _M_tp; 427 }; 428 429 // Support for custom deleter and/or allocator 430 template<typename _Ptr, typename _Deleter, typename _Alloc, _Lock_policy _Lp> 431 class _Sp_counted_deleter final : public _Sp_counted_base<_Lp> 432 { 433 class _Impl : _Sp_ebo_helper<0, _Deleter>, _Sp_ebo_helper<1, _Alloc> 434 { 435 typedef _Sp_ebo_helper<0, _Deleter> _Del_base; 436 typedef _Sp_ebo_helper<1, _Alloc> _Alloc_base; 437 438 public: 439 _Impl(_Ptr __p, _Deleter __d, const _Alloc& __a) noexcept 440 : _M_ptr(__p), _Del_base(__d), _Alloc_base(__a) 441 { } 442 443 _Deleter& _M_del() noexcept { return _Del_base::_S_get(*this); } 444 _Alloc& _M_alloc() noexcept { return _Alloc_base::_S_get(*this); } 445 446 _Ptr _M_ptr; 447 }; 448 449 public: 450 using __allocator_type = __alloc_rebind<_Alloc, _Sp_counted_deleter>; 451 452 // __d(__p) must not throw. 453 _Sp_counted_deleter(_Ptr __p, _Deleter __d) noexcept 454 : _M_impl(__p, __d, _Alloc()) { } 455 456 // __d(__p) must not throw. 457 _Sp_counted_deleter(_Ptr __p, _Deleter __d, const _Alloc& __a) noexcept 458 : _M_impl(__p, __d, __a) { } 459 460 ~_Sp_counted_deleter() noexcept { } 461 462 virtual void 463 _M_dispose() noexcept 464 { _M_impl._M_del()(_M_impl._M_ptr); } 465 466 virtual void 467 _M_destroy() noexcept 468 { 469 __allocator_type __a(_M_impl._M_alloc()); 470 __allocated_ptr<__allocator_type> __guard_ptr{ __a, this }; 471 this->~_Sp_counted_deleter(); 472 } 473 474 virtual void* 475 _M_get_deleter(const std::type_info& __ti) noexcept 476 { 477 #if __cpp_rtti 478 // _GLIBCXX_RESOLVE_LIB_DEFECTS 479 // 2400. shared_ptr's get_deleter() should use addressof() 480 return __ti == typeid(_Deleter) 481 ? std::__addressof(_M_impl._M_del()) 482 : nullptr; 483 #else 484 return nullptr; 485 #endif 486 } 487 488 private: 489 _Impl _M_impl; 490 }; 491 492 // helpers for make_shared / allocate_shared 493 494 struct _Sp_make_shared_tag { }; 495 496 template<typename _Tp, typename _Alloc, _Lock_policy _Lp> 497 class _Sp_counted_ptr_inplace final : public _Sp_counted_base<_Lp> 498 { 499 class _Impl : _Sp_ebo_helper<0, _Alloc> 500 { 501 typedef _Sp_ebo_helper<0, _Alloc> _A_base; 502 503 public: 504 explicit _Impl(_Alloc __a) noexcept : _A_base(__a) { } 505 506 _Alloc& _M_alloc() noexcept { return _A_base::_S_get(*this); } 507 508 __gnu_cxx::__aligned_buffer<_Tp> _M_storage; 509 }; 510 511 public: 512 using __allocator_type = __alloc_rebind<_Alloc, _Sp_counted_ptr_inplace>; 513 514 template<typename... _Args> 515 _Sp_counted_ptr_inplace(_Alloc __a, _Args&&... __args) 516 : _M_impl(__a) 517 { 518 // _GLIBCXX_RESOLVE_LIB_DEFECTS 519 // 2070. allocate_shared should use allocator_traits<A>::construct 520 allocator_traits<_Alloc>::construct(__a, _M_ptr(), 521 std::forward<_Args>(__args)...); // might throw 522 } 523 524 ~_Sp_counted_ptr_inplace() noexcept { } 525 526 virtual void 527 _M_dispose() noexcept 528 { 529 allocator_traits<_Alloc>::destroy(_M_impl._M_alloc(), _M_ptr()); 530 } 531 532 // Override because the allocator needs to know the dynamic type 533 virtual void 534 _M_destroy() noexcept 535 { 536 __allocator_type __a(_M_impl._M_alloc()); 537 __allocated_ptr<__allocator_type> __guard_ptr{ __a, this }; 538 this->~_Sp_counted_ptr_inplace(); 539 } 540 541 // Sneaky trick so __shared_ptr can get the managed pointer 542 virtual void* 543 _M_get_deleter(const std::type_info& __ti) noexcept 544 { 545 #if __cpp_rtti 546 if (__ti == typeid(_Sp_make_shared_tag)) 547 return const_cast<typename remove_cv<_Tp>::type*>(_M_ptr()); 548 #endif 549 return nullptr; 550 } 551 552 private: 553 _Tp* _M_ptr() noexcept { return _M_impl._M_storage._M_ptr(); } 554 555 _Impl _M_impl; 556 }; 557 558 559 template<_Lock_policy _Lp> 560 class __shared_count 561 { 562 public: 563 constexpr __shared_count() noexcept : _M_pi(0) 564 { } 565 566 template<typename _Ptr> 567 explicit 568 __shared_count(_Ptr __p) : _M_pi(0) 569 { 570 __try 571 { 572 _M_pi = new _Sp_counted_ptr<_Ptr, _Lp>(__p); 573 } 574 __catch(...) 575 { 576 delete __p; 577 __throw_exception_again; 578 } 579 } 580 581 template<typename _Ptr, typename _Deleter> 582 __shared_count(_Ptr __p, _Deleter __d) 583 : __shared_count(__p, std::move(__d), allocator<void>()) 584 { } 585 586 template<typename _Ptr, typename _Deleter, typename _Alloc> 587 __shared_count(_Ptr __p, _Deleter __d, _Alloc __a) : _M_pi(0) 588 { 589 typedef _Sp_counted_deleter<_Ptr, _Deleter, _Alloc, _Lp> _Sp_cd_type; 590 __try 591 { 592 typename _Sp_cd_type::__allocator_type __a2(__a); 593 auto __guard = std::__allocate_guarded(__a2); 594 _Sp_cd_type* __mem = __guard.get(); 595 ::new (__mem) _Sp_cd_type(__p, std::move(__d), std::move(__a)); 596 _M_pi = __mem; 597 __guard = nullptr; 598 } 599 __catch(...) 600 { 601 __d(__p); // Call _Deleter on __p. 602 __throw_exception_again; 603 } 604 } 605 606 template<typename _Tp, typename _Alloc, typename... _Args> 607 __shared_count(_Sp_make_shared_tag, _Tp*, const _Alloc& __a, 608 _Args&&... __args) 609 : _M_pi(0) 610 { 611 typedef _Sp_counted_ptr_inplace<_Tp, _Alloc, _Lp> _Sp_cp_type; 612 typename _Sp_cp_type::__allocator_type __a2(__a); 613 auto __guard = std::__allocate_guarded(__a2); 614 _Sp_cp_type* __mem = __guard.get(); 615 ::new (__mem) _Sp_cp_type(std::move(__a), 616 std::forward<_Args>(__args)...); 617 _M_pi = __mem; 618 __guard = nullptr; 619 } 620 621 #if _GLIBCXX_USE_DEPRECATED 622 // Special case for auto_ptr<_Tp> to provide the strong guarantee. 623 template<typename _Tp> 624 explicit 625 __shared_count(std::auto_ptr<_Tp>&& __r); 626 #endif 627 628 // Special case for unique_ptr<_Tp,_Del> to provide the strong guarantee. 629 template<typename _Tp, typename _Del> 630 explicit 631 __shared_count(std::unique_ptr<_Tp, _Del>&& __r) : _M_pi(0) 632 { 633 // _GLIBCXX_RESOLVE_LIB_DEFECTS 634 // 2415. Inconsistency between unique_ptr and shared_ptr 635 if (__r.get() == nullptr) 636 return; 637 638 using _Ptr = typename unique_ptr<_Tp, _Del>::pointer; 639 using _Del2 = typename conditional<is_reference<_Del>::value, 640 reference_wrapper<typename remove_reference<_Del>::type>, 641 _Del>::type; 642 using _Sp_cd_type 643 = _Sp_counted_deleter<_Ptr, _Del2, allocator<void>, _Lp>; 644 using _Alloc = allocator<_Sp_cd_type>; 645 using _Alloc_traits = allocator_traits<_Alloc>; 646 _Alloc __a; 647 _Sp_cd_type* __mem = _Alloc_traits::allocate(__a, 1); 648 _Alloc_traits::construct(__a, __mem, __r.release(), 649 __r.get_deleter()); // non-throwing 650 _M_pi = __mem; 651 } 652 653 // Throw bad_weak_ptr when __r._M_get_use_count() == 0. 654 explicit __shared_count(const __weak_count<_Lp>& __r); 655 656 // Does not throw if __r._M_get_use_count() == 0, caller must check. 657 explicit __shared_count(const __weak_count<_Lp>& __r, std::nothrow_t); 658 659 ~__shared_count() noexcept 660 { 661 if (_M_pi != nullptr) 662 _M_pi->_M_release(); 663 } 664 665 __shared_count(const __shared_count& __r) noexcept 666 : _M_pi(__r._M_pi) 667 { 668 if (_M_pi != 0) 669 _M_pi->_M_add_ref_copy(); 670 } 671 672 __shared_count& 673 operator=(const __shared_count& __r) noexcept 674 { 675 _Sp_counted_base<_Lp>* __tmp = __r._M_pi; 676 if (__tmp != _M_pi) 677 { 678 if (__tmp != 0) 679 __tmp->_M_add_ref_copy(); 680 if (_M_pi != 0) 681 _M_pi->_M_release(); 682 _M_pi = __tmp; 683 } 684 return *this; 685 } 686 687 void 688 _M_swap(__shared_count& __r) noexcept 689 { 690 _Sp_counted_base<_Lp>* __tmp = __r._M_pi; 691 __r._M_pi = _M_pi; 692 _M_pi = __tmp; 693 } 694 695 long 696 _M_get_use_count() const noexcept 697 { return _M_pi != 0 ? _M_pi->_M_get_use_count() : 0; } 698 699 bool 700 _M_unique() const noexcept 701 { return this->_M_get_use_count() == 1; } 702 703 void* 704 _M_get_deleter(const std::type_info& __ti) const noexcept 705 { return _M_pi ? _M_pi->_M_get_deleter(__ti) : nullptr; } 706 707 bool 708 _M_less(const __shared_count& __rhs) const noexcept 709 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); } 710 711 bool 712 _M_less(const __weak_count<_Lp>& __rhs) const noexcept 713 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); } 714 715 // Friend function injected into enclosing namespace and found by ADL 716 friend inline bool 717 operator==(const __shared_count& __a, const __shared_count& __b) noexcept 718 { return __a._M_pi == __b._M_pi; } 719 720 private: 721 friend class __weak_count<_Lp>; 722 723 _Sp_counted_base<_Lp>* _M_pi; 724 }; 725 726 727 template<_Lock_policy _Lp> 728 class __weak_count 729 { 730 public: 731 constexpr __weak_count() noexcept : _M_pi(nullptr) 732 { } 733 734 __weak_count(const __shared_count<_Lp>& __r) noexcept 735 : _M_pi(__r._M_pi) 736 { 737 if (_M_pi != nullptr) 738 _M_pi->_M_weak_add_ref(); 739 } 740 741 __weak_count(const __weak_count& __r) noexcept 742 : _M_pi(__r._M_pi) 743 { 744 if (_M_pi != nullptr) 745 _M_pi->_M_weak_add_ref(); 746 } 747 748 __weak_count(__weak_count&& __r) noexcept 749 : _M_pi(__r._M_pi) 750 { __r._M_pi = nullptr; } 751 752 ~__weak_count() noexcept 753 { 754 if (_M_pi != nullptr) 755 _M_pi->_M_weak_release(); 756 } 757 758 __weak_count& 759 operator=(const __shared_count<_Lp>& __r) noexcept 760 { 761 _Sp_counted_base<_Lp>* __tmp = __r._M_pi; 762 if (__tmp != nullptr) 763 __tmp->_M_weak_add_ref(); 764 if (_M_pi != nullptr) 765 _M_pi->_M_weak_release(); 766 _M_pi = __tmp; 767 return *this; 768 } 769 770 __weak_count& 771 operator=(const __weak_count& __r) noexcept 772 { 773 _Sp_counted_base<_Lp>* __tmp = __r._M_pi; 774 if (__tmp != nullptr) 775 __tmp->_M_weak_add_ref(); 776 if (_M_pi != nullptr) 777 _M_pi->_M_weak_release(); 778 _M_pi = __tmp; 779 return *this; 780 } 781 782 __weak_count& 783 operator=(__weak_count&& __r) noexcept 784 { 785 if (_M_pi != nullptr) 786 _M_pi->_M_weak_release(); 787 _M_pi = __r._M_pi; 788 __r._M_pi = nullptr; 789 return *this; 790 } 791 792 void 793 _M_swap(__weak_count& __r) noexcept 794 { 795 _Sp_counted_base<_Lp>* __tmp = __r._M_pi; 796 __r._M_pi = _M_pi; 797 _M_pi = __tmp; 798 } 799 800 long 801 _M_get_use_count() const noexcept 802 { return _M_pi != nullptr ? _M_pi->_M_get_use_count() : 0; } 803 804 bool 805 _M_less(const __weak_count& __rhs) const noexcept 806 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); } 807 808 bool 809 _M_less(const __shared_count<_Lp>& __rhs) const noexcept 810 { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); } 811 812 // Friend function injected into enclosing namespace and found by ADL 813 friend inline bool 814 operator==(const __weak_count& __a, const __weak_count& __b) noexcept 815 { return __a._M_pi == __b._M_pi; } 816 817 private: 818 friend class __shared_count<_Lp>; 819 820 _Sp_counted_base<_Lp>* _M_pi; 821 }; 822 823 // Now that __weak_count is defined we can define this constructor: 824 template<_Lock_policy _Lp> 825 inline 826 __shared_count<_Lp>::__shared_count(const __weak_count<_Lp>& __r) 827 : _M_pi(__r._M_pi) 828 { 829 if (_M_pi != nullptr) 830 _M_pi->_M_add_ref_lock(); 831 else 832 __throw_bad_weak_ptr(); 833 } 834 835 // Now that __weak_count is defined we can define this constructor: 836 template<_Lock_policy _Lp> 837 inline 838 __shared_count<_Lp>:: 839 __shared_count(const __weak_count<_Lp>& __r, std::nothrow_t) 840 : _M_pi(__r._M_pi) 841 { 842 if (_M_pi != nullptr) 843 if (!_M_pi->_M_add_ref_lock_nothrow()) 844 _M_pi = nullptr; 845 } 846 847 // Support for enable_shared_from_this. 848 849 // Friend of __enable_shared_from_this. 850 template<_Lock_policy _Lp, typename _Tp1, typename _Tp2> 851 void 852 __enable_shared_from_this_helper(const __shared_count<_Lp>&, 853 const __enable_shared_from_this<_Tp1, 854 _Lp>*, const _Tp2*) noexcept; 855 856 // Friend of enable_shared_from_this. 857 template<typename _Tp1, typename _Tp2> 858 void 859 __enable_shared_from_this_helper(const __shared_count<>&, 860 const enable_shared_from_this<_Tp1>*, 861 const _Tp2*) noexcept; 862 863 template<_Lock_policy _Lp> 864 inline void 865 __enable_shared_from_this_helper(const __shared_count<_Lp>&, ...) noexcept 866 { } 867 868 869 template<typename _Tp, _Lock_policy _Lp> 870 class __shared_ptr 871 { 872 template<typename _Ptr> 873 using _Convertible 874 = typename enable_if<is_convertible<_Ptr, _Tp*>::value>::type; 875 876 public: 877 typedef _Tp element_type; 878 879 constexpr __shared_ptr() noexcept 880 : _M_ptr(0), _M_refcount() 881 { } 882 883 template<typename _Tp1> 884 explicit __shared_ptr(_Tp1* __p) 885 : _M_ptr(__p), _M_refcount(__p) 886 { 887 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>) 888 static_assert( !is_void<_Tp1>::value, "incomplete type" ); 889 static_assert( sizeof(_Tp1) > 0, "incomplete type" ); 890 __enable_shared_from_this_helper(_M_refcount, __p, __p); 891 } 892 893 template<typename _Tp1, typename _Deleter> 894 __shared_ptr(_Tp1* __p, _Deleter __d) 895 : _M_ptr(__p), _M_refcount(__p, __d) 896 { 897 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>) 898 // TODO requires _Deleter CopyConstructible and __d(__p) well-formed 899 __enable_shared_from_this_helper(_M_refcount, __p, __p); 900 } 901 902 template<typename _Tp1, typename _Deleter, typename _Alloc> 903 __shared_ptr(_Tp1* __p, _Deleter __d, _Alloc __a) 904 : _M_ptr(__p), _M_refcount(__p, __d, std::move(__a)) 905 { 906 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>) 907 // TODO requires _Deleter CopyConstructible and __d(__p) well-formed 908 __enable_shared_from_this_helper(_M_refcount, __p, __p); 909 } 910 911 template<typename _Deleter> 912 __shared_ptr(nullptr_t __p, _Deleter __d) 913 : _M_ptr(0), _M_refcount(__p, __d) 914 { } 915 916 template<typename _Deleter, typename _Alloc> 917 __shared_ptr(nullptr_t __p, _Deleter __d, _Alloc __a) 918 : _M_ptr(0), _M_refcount(__p, __d, std::move(__a)) 919 { } 920 921 template<typename _Tp1> 922 __shared_ptr(const __shared_ptr<_Tp1, _Lp>& __r, _Tp* __p) noexcept 923 : _M_ptr(__p), _M_refcount(__r._M_refcount) // never throws 924 { } 925 926 __shared_ptr(const __shared_ptr&) noexcept = default; 927 __shared_ptr& operator=(const __shared_ptr&) noexcept = default; 928 ~__shared_ptr() = default; 929 930 template<typename _Tp1, typename = _Convertible<_Tp1*>> 931 __shared_ptr(const __shared_ptr<_Tp1, _Lp>& __r) noexcept 932 : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount) 933 { } 934 935 __shared_ptr(__shared_ptr&& __r) noexcept 936 : _M_ptr(__r._M_ptr), _M_refcount() 937 { 938 _M_refcount._M_swap(__r._M_refcount); 939 __r._M_ptr = 0; 940 } 941 942 template<typename _Tp1, typename = _Convertible<_Tp1*>> 943 __shared_ptr(__shared_ptr<_Tp1, _Lp>&& __r) noexcept 944 : _M_ptr(__r._M_ptr), _M_refcount() 945 { 946 _M_refcount._M_swap(__r._M_refcount); 947 __r._M_ptr = 0; 948 } 949 950 template<typename _Tp1> 951 explicit __shared_ptr(const __weak_ptr<_Tp1, _Lp>& __r) 952 : _M_refcount(__r._M_refcount) // may throw 953 { 954 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>) 955 956 // It is now safe to copy __r._M_ptr, as 957 // _M_refcount(__r._M_refcount) did not throw. 958 _M_ptr = __r._M_ptr; 959 } 960 961 // If an exception is thrown this constructor has no effect. 962 template<typename _Tp1, typename _Del, typename 963 = _Convertible<typename unique_ptr<_Tp1, _Del>::pointer>> 964 __shared_ptr(std::unique_ptr<_Tp1, _Del>&& __r) 965 : _M_ptr(__r.get()), _M_refcount() 966 { 967 __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>) 968 auto __raw = _S_raw_ptr(__r.get()); 969 _M_refcount = __shared_count<_Lp>(std::move(__r)); 970 __enable_shared_from_this_helper(_M_refcount, __raw, __raw); 971 } 972 973 #if _GLIBCXX_USE_DEPRECATED 974 // Postcondition: use_count() == 1 and __r.get() == 0 975 template<typename _Tp1> 976 __shared_ptr(std::auto_ptr<_Tp1>&& __r); 977 #endif 978 979 constexpr __shared_ptr(nullptr_t) noexcept : __shared_ptr() { } 980 981 template<typename _Tp1> 982 __shared_ptr& 983 operator=(const __shared_ptr<_Tp1, _Lp>& __r) noexcept 984 { 985 _M_ptr = __r._M_ptr; 986 _M_refcount = __r._M_refcount; // __shared_count::op= doesn't throw 987 return *this; 988 } 989 990 #if _GLIBCXX_USE_DEPRECATED 991 template<typename _Tp1> 992 __shared_ptr& 993 operator=(std::auto_ptr<_Tp1>&& __r) 994 { 995 __shared_ptr(std::move(__r)).swap(*this); 996 return *this; 997 } 998 #endif 999 1000 __shared_ptr& 1001 operator=(__shared_ptr&& __r) noexcept 1002 { 1003 __shared_ptr(std::move(__r)).swap(*this); 1004 return *this; 1005 } 1006 1007 template<class _Tp1> 1008 __shared_ptr& 1009 operator=(__shared_ptr<_Tp1, _Lp>&& __r) noexcept 1010 { 1011 __shared_ptr(std::move(__r)).swap(*this); 1012 return *this; 1013 } 1014 1015 template<typename _Tp1, typename _Del> 1016 __shared_ptr& 1017 operator=(std::unique_ptr<_Tp1, _Del>&& __r) 1018 { 1019 __shared_ptr(std::move(__r)).swap(*this); 1020 return *this; 1021 } 1022 1023 void 1024 reset() noexcept 1025 { __shared_ptr().swap(*this); } 1026 1027 template<typename _Tp1> 1028 void 1029 reset(_Tp1* __p) // _Tp1 must be complete. 1030 { 1031 // Catch self-reset errors. 1032 __glibcxx_assert(__p == 0 || __p != _M_ptr); 1033 __shared_ptr(__p).swap(*this); 1034 } 1035 1036 template<typename _Tp1, typename _Deleter> 1037 void 1038 reset(_Tp1* __p, _Deleter __d) 1039 { __shared_ptr(__p, __d).swap(*this); } 1040 1041 template<typename _Tp1, typename _Deleter, typename _Alloc> 1042 void 1043 reset(_Tp1* __p, _Deleter __d, _Alloc __a) 1044 { __shared_ptr(__p, __d, std::move(__a)).swap(*this); } 1045 1046 // Allow class instantiation when _Tp is [cv-qual] void. 1047 typename std::add_lvalue_reference<_Tp>::type 1048 operator*() const noexcept 1049 { 1050 __glibcxx_assert(_M_ptr != 0); 1051 return *_M_ptr; 1052 } 1053 1054 _Tp* 1055 operator->() const noexcept 1056 { 1057 _GLIBCXX_DEBUG_PEDASSERT(_M_ptr != 0); 1058 return _M_ptr; 1059 } 1060 1061 _Tp* 1062 get() const noexcept 1063 { return _M_ptr; } 1064 1065 explicit operator bool() const // never throws 1066 { return _M_ptr == 0 ? false : true; } 1067 1068 bool 1069 unique() const noexcept 1070 { return _M_refcount._M_unique(); } 1071 1072 long 1073 use_count() const noexcept 1074 { return _M_refcount._M_get_use_count(); } 1075 1076 void 1077 swap(__shared_ptr<_Tp, _Lp>& __other) noexcept 1078 { 1079 std::swap(_M_ptr, __other._M_ptr); 1080 _M_refcount._M_swap(__other._M_refcount); 1081 } 1082 1083 template<typename _Tp1> 1084 bool 1085 owner_before(__shared_ptr<_Tp1, _Lp> const& __rhs) const noexcept 1086 { return _M_refcount._M_less(__rhs._M_refcount); } 1087 1088 template<typename _Tp1> 1089 bool 1090 owner_before(__weak_ptr<_Tp1, _Lp> const& __rhs) const noexcept 1091 { return _M_refcount._M_less(__rhs._M_refcount); } 1092 1093 #if __cpp_rtti 1094 protected: 1095 // This constructor is non-standard, it is used by allocate_shared. 1096 template<typename _Alloc, typename... _Args> 1097 __shared_ptr(_Sp_make_shared_tag __tag, const _Alloc& __a, 1098 _Args&&... __args) 1099 : _M_ptr(), _M_refcount(__tag, (_Tp*)0, __a, 1100 std::forward<_Args>(__args)...) 1101 { 1102 // _M_ptr needs to point to the newly constructed object. 1103 // This relies on _Sp_counted_ptr_inplace::_M_get_deleter. 1104 void* __p = _M_refcount._M_get_deleter(typeid(__tag)); 1105 _M_ptr = static_cast<_Tp*>(__p); 1106 __enable_shared_from_this_helper(_M_refcount, _M_ptr, _M_ptr); 1107 } 1108 #else 1109 template<typename _Alloc> 1110 struct _Deleter 1111 { 1112 void operator()(typename _Alloc::value_type* __ptr) 1113 { 1114 __allocated_ptr<_Alloc> __guard{ _M_alloc, __ptr }; 1115 allocator_traits<_Alloc>::destroy(_M_alloc, __guard.get()); 1116 } 1117 _Alloc _M_alloc; 1118 }; 1119 1120 template<typename _Alloc, typename... _Args> 1121 __shared_ptr(_Sp_make_shared_tag __tag, const _Alloc& __a, 1122 _Args&&... __args) 1123 : _M_ptr(), _M_refcount() 1124 { 1125 typedef typename allocator_traits<_Alloc>::template 1126 rebind_traits<typename std::remove_cv<_Tp>::type> __traits; 1127 _Deleter<typename __traits::allocator_type> __del = { __a }; 1128 auto __guard = std::__allocate_guarded(__del._M_alloc); 1129 auto __ptr = __guard.get(); 1130 // _GLIBCXX_RESOLVE_LIB_DEFECTS 1131 // 2070. allocate_shared should use allocator_traits<A>::construct 1132 __traits::construct(__del._M_alloc, __ptr, 1133 std::forward<_Args>(__args)...); 1134 __guard = nullptr; 1135 __shared_count<_Lp> __count(__ptr, __del, __del._M_alloc); 1136 _M_refcount._M_swap(__count); 1137 _M_ptr = __ptr; 1138 __enable_shared_from_this_helper(_M_refcount, _M_ptr, _M_ptr); 1139 } 1140 #endif 1141 1142 template<typename _Tp1, _Lock_policy _Lp1, typename _Alloc, 1143 typename... _Args> 1144 friend __shared_ptr<_Tp1, _Lp1> 1145 __allocate_shared(const _Alloc& __a, _Args&&... __args); 1146 1147 // This constructor is used by __weak_ptr::lock() and 1148 // shared_ptr::shared_ptr(const weak_ptr&, std::nothrow_t). 1149 __shared_ptr(const __weak_ptr<_Tp, _Lp>& __r, std::nothrow_t) 1150 : _M_refcount(__r._M_refcount, std::nothrow) 1151 { 1152 _M_ptr = _M_refcount._M_get_use_count() ? __r._M_ptr : nullptr; 1153 } 1154 1155 friend class __weak_ptr<_Tp, _Lp>; 1156 1157 private: 1158 void* 1159 _M_get_deleter(const std::type_info& __ti) const noexcept 1160 { return _M_refcount._M_get_deleter(__ti); } 1161 1162 template<typename _Tp1> 1163 static _Tp1* 1164 _S_raw_ptr(_Tp1* __ptr) 1165 { return __ptr; } 1166 1167 template<typename _Tp1> 1168 static auto 1169 _S_raw_ptr(_Tp1 __ptr) -> decltype(std::__addressof(*__ptr)) 1170 { return std::__addressof(*__ptr); } 1171 1172 template<typename _Tp1, _Lock_policy _Lp1> friend class __shared_ptr; 1173 template<typename _Tp1, _Lock_policy _Lp1> friend class __weak_ptr; 1174 1175 template<typename _Del, typename _Tp1, _Lock_policy _Lp1> 1176 friend _Del* get_deleter(const __shared_ptr<_Tp1, _Lp1>&) noexcept; 1177 1178 _Tp* _M_ptr; // Contained pointer. 1179 __shared_count<_Lp> _M_refcount; // Reference counter. 1180 }; 1181 1182 1183 // 20.7.2.2.7 shared_ptr comparisons 1184 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp> 1185 inline bool 1186 operator==(const __shared_ptr<_Tp1, _Lp>& __a, 1187 const __shared_ptr<_Tp2, _Lp>& __b) noexcept 1188 { return __a.get() == __b.get(); } 1189 1190 template<typename _Tp, _Lock_policy _Lp> 1191 inline bool 1192 operator==(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept 1193 { return !__a; } 1194 1195 template<typename _Tp, _Lock_policy _Lp> 1196 inline bool 1197 operator==(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept 1198 { return !__a; } 1199 1200 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp> 1201 inline bool 1202 operator!=(const __shared_ptr<_Tp1, _Lp>& __a, 1203 const __shared_ptr<_Tp2, _Lp>& __b) noexcept 1204 { return __a.get() != __b.get(); } 1205 1206 template<typename _Tp, _Lock_policy _Lp> 1207 inline bool 1208 operator!=(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept 1209 { return (bool)__a; } 1210 1211 template<typename _Tp, _Lock_policy _Lp> 1212 inline bool 1213 operator!=(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept 1214 { return (bool)__a; } 1215 1216 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp> 1217 inline bool 1218 operator<(const __shared_ptr<_Tp1, _Lp>& __a, 1219 const __shared_ptr<_Tp2, _Lp>& __b) noexcept 1220 { 1221 typedef typename std::common_type<_Tp1*, _Tp2*>::type _CT; 1222 return std::less<_CT>()(__a.get(), __b.get()); 1223 } 1224 1225 template<typename _Tp, _Lock_policy _Lp> 1226 inline bool 1227 operator<(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept 1228 { return std::less<_Tp*>()(__a.get(), nullptr); } 1229 1230 template<typename _Tp, _Lock_policy _Lp> 1231 inline bool 1232 operator<(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept 1233 { return std::less<_Tp*>()(nullptr, __a.get()); } 1234 1235 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp> 1236 inline bool 1237 operator<=(const __shared_ptr<_Tp1, _Lp>& __a, 1238 const __shared_ptr<_Tp2, _Lp>& __b) noexcept 1239 { return !(__b < __a); } 1240 1241 template<typename _Tp, _Lock_policy _Lp> 1242 inline bool 1243 operator<=(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept 1244 { return !(nullptr < __a); } 1245 1246 template<typename _Tp, _Lock_policy _Lp> 1247 inline bool 1248 operator<=(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept 1249 { return !(__a < nullptr); } 1250 1251 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp> 1252 inline bool 1253 operator>(const __shared_ptr<_Tp1, _Lp>& __a, 1254 const __shared_ptr<_Tp2, _Lp>& __b) noexcept 1255 { return (__b < __a); } 1256 1257 template<typename _Tp, _Lock_policy _Lp> 1258 inline bool 1259 operator>(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept 1260 { return std::less<_Tp*>()(nullptr, __a.get()); } 1261 1262 template<typename _Tp, _Lock_policy _Lp> 1263 inline bool 1264 operator>(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept 1265 { return std::less<_Tp*>()(__a.get(), nullptr); } 1266 1267 template<typename _Tp1, typename _Tp2, _Lock_policy _Lp> 1268 inline bool 1269 operator>=(const __shared_ptr<_Tp1, _Lp>& __a, 1270 const __shared_ptr<_Tp2, _Lp>& __b) noexcept 1271 { return !(__a < __b); } 1272 1273 template<typename _Tp, _Lock_policy _Lp> 1274 inline bool 1275 operator>=(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept 1276 { return !(__a < nullptr); } 1277 1278 template<typename _Tp, _Lock_policy _Lp> 1279 inline bool 1280 operator>=(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept 1281 { return !(nullptr < __a); } 1282 1283 template<typename _Sp> 1284 struct _Sp_less : public binary_function<_Sp, _Sp, bool> 1285 { 1286 bool 1287 operator()(const _Sp& __lhs, const _Sp& __rhs) const noexcept 1288 { 1289 typedef typename _Sp::element_type element_type; 1290 return std::less<element_type*>()(__lhs.get(), __rhs.get()); 1291 } 1292 }; 1293 1294 template<typename _Tp, _Lock_policy _Lp> 1295 struct less<__shared_ptr<_Tp, _Lp>> 1296 : public _Sp_less<__shared_ptr<_Tp, _Lp>> 1297 { }; 1298 1299 // 20.7.2.2.8 shared_ptr specialized algorithms. 1300 template<typename _Tp, _Lock_policy _Lp> 1301 inline void 1302 swap(__shared_ptr<_Tp, _Lp>& __a, __shared_ptr<_Tp, _Lp>& __b) noexcept 1303 { __a.swap(__b); } 1304 1305 // 20.7.2.2.9 shared_ptr casts 1306 1307 // The seemingly equivalent code: 1308 // shared_ptr<_Tp, _Lp>(static_cast<_Tp*>(__r.get())) 1309 // will eventually result in undefined behaviour, attempting to 1310 // delete the same object twice. 1311 /// static_pointer_cast 1312 template<typename _Tp, typename _Tp1, _Lock_policy _Lp> 1313 inline __shared_ptr<_Tp, _Lp> 1314 static_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept 1315 { return __shared_ptr<_Tp, _Lp>(__r, static_cast<_Tp*>(__r.get())); } 1316 1317 // The seemingly equivalent code: 1318 // shared_ptr<_Tp, _Lp>(const_cast<_Tp*>(__r.get())) 1319 // will eventually result in undefined behaviour, attempting to 1320 // delete the same object twice. 1321 /// const_pointer_cast 1322 template<typename _Tp, typename _Tp1, _Lock_policy _Lp> 1323 inline __shared_ptr<_Tp, _Lp> 1324 const_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept 1325 { return __shared_ptr<_Tp, _Lp>(__r, const_cast<_Tp*>(__r.get())); } 1326 1327 // The seemingly equivalent code: 1328 // shared_ptr<_Tp, _Lp>(dynamic_cast<_Tp*>(__r.get())) 1329 // will eventually result in undefined behaviour, attempting to 1330 // delete the same object twice. 1331 /// dynamic_pointer_cast 1332 template<typename _Tp, typename _Tp1, _Lock_policy _Lp> 1333 inline __shared_ptr<_Tp, _Lp> 1334 dynamic_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept 1335 { 1336 if (_Tp* __p = dynamic_cast<_Tp*>(__r.get())) 1337 return __shared_ptr<_Tp, _Lp>(__r, __p); 1338 return __shared_ptr<_Tp, _Lp>(); 1339 } 1340 1341 1342 template<typename _Tp, _Lock_policy _Lp> 1343 class __weak_ptr 1344 { 1345 template<typename _Ptr> 1346 using _Convertible 1347 = typename enable_if<is_convertible<_Ptr, _Tp*>::value>::type; 1348 1349 public: 1350 typedef _Tp element_type; 1351 1352 constexpr __weak_ptr() noexcept 1353 : _M_ptr(nullptr), _M_refcount() 1354 { } 1355 1356 __weak_ptr(const __weak_ptr&) noexcept = default; 1357 1358 ~__weak_ptr() = default; 1359 1360 // The "obvious" converting constructor implementation: 1361 // 1362 // template<typename _Tp1> 1363 // __weak_ptr(const __weak_ptr<_Tp1, _Lp>& __r) 1364 // : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount) // never throws 1365 // { } 1366 // 1367 // has a serious problem. 1368 // 1369 // __r._M_ptr may already have been invalidated. The _M_ptr(__r._M_ptr) 1370 // conversion may require access to *__r._M_ptr (virtual inheritance). 1371 // 1372 // It is not possible to avoid spurious access violations since 1373 // in multithreaded programs __r._M_ptr may be invalidated at any point. 1374 template<typename _Tp1, typename = _Convertible<_Tp1*>> 1375 __weak_ptr(const __weak_ptr<_Tp1, _Lp>& __r) noexcept 1376 : _M_refcount(__r._M_refcount) 1377 { _M_ptr = __r.lock().get(); } 1378 1379 template<typename _Tp1, typename = _Convertible<_Tp1*>> 1380 __weak_ptr(const __shared_ptr<_Tp1, _Lp>& __r) noexcept 1381 : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount) 1382 { } 1383 1384 __weak_ptr(__weak_ptr&& __r) noexcept 1385 : _M_ptr(__r._M_ptr), _M_refcount(std::move(__r._M_refcount)) 1386 { __r._M_ptr = nullptr; } 1387 1388 template<typename _Tp1, typename = _Convertible<_Tp1*>> 1389 __weak_ptr(__weak_ptr<_Tp1, _Lp>&& __r) noexcept 1390 : _M_ptr(__r.lock().get()), _M_refcount(std::move(__r._M_refcount)) 1391 { __r._M_ptr = nullptr; } 1392 1393 __weak_ptr& 1394 operator=(const __weak_ptr& __r) noexcept = default; 1395 1396 template<typename _Tp1> 1397 __weak_ptr& 1398 operator=(const __weak_ptr<_Tp1, _Lp>& __r) noexcept 1399 { 1400 _M_ptr = __r.lock().get(); 1401 _M_refcount = __r._M_refcount; 1402 return *this; 1403 } 1404 1405 template<typename _Tp1> 1406 __weak_ptr& 1407 operator=(const __shared_ptr<_Tp1, _Lp>& __r) noexcept 1408 { 1409 _M_ptr = __r._M_ptr; 1410 _M_refcount = __r._M_refcount; 1411 return *this; 1412 } 1413 1414 __weak_ptr& 1415 operator=(__weak_ptr&& __r) noexcept 1416 { 1417 _M_ptr = __r._M_ptr; 1418 _M_refcount = std::move(__r._M_refcount); 1419 __r._M_ptr = nullptr; 1420 return *this; 1421 } 1422 1423 template<typename _Tp1> 1424 __weak_ptr& 1425 operator=(__weak_ptr<_Tp1, _Lp>&& __r) noexcept 1426 { 1427 _M_ptr = __r.lock().get(); 1428 _M_refcount = std::move(__r._M_refcount); 1429 __r._M_ptr = nullptr; 1430 return *this; 1431 } 1432 1433 __shared_ptr<_Tp, _Lp> 1434 lock() const noexcept 1435 { return __shared_ptr<element_type, _Lp>(*this, std::nothrow); } 1436 1437 long 1438 use_count() const noexcept 1439 { return _M_refcount._M_get_use_count(); } 1440 1441 bool 1442 expired() const noexcept 1443 { return _M_refcount._M_get_use_count() == 0; } 1444 1445 template<typename _Tp1> 1446 bool 1447 owner_before(const __shared_ptr<_Tp1, _Lp>& __rhs) const noexcept 1448 { return _M_refcount._M_less(__rhs._M_refcount); } 1449 1450 template<typename _Tp1> 1451 bool 1452 owner_before(const __weak_ptr<_Tp1, _Lp>& __rhs) const noexcept 1453 { return _M_refcount._M_less(__rhs._M_refcount); } 1454 1455 void 1456 reset() noexcept 1457 { __weak_ptr().swap(*this); } 1458 1459 void 1460 swap(__weak_ptr& __s) noexcept 1461 { 1462 std::swap(_M_ptr, __s._M_ptr); 1463 _M_refcount._M_swap(__s._M_refcount); 1464 } 1465 1466 private: 1467 // Used by __enable_shared_from_this. 1468 void 1469 _M_assign(_Tp* __ptr, const __shared_count<_Lp>& __refcount) noexcept 1470 { 1471 if (use_count() == 0) 1472 { 1473 _M_ptr = __ptr; 1474 _M_refcount = __refcount; 1475 } 1476 } 1477 1478 template<typename _Tp1, _Lock_policy _Lp1> friend class __shared_ptr; 1479 template<typename _Tp1, _Lock_policy _Lp1> friend class __weak_ptr; 1480 friend class __enable_shared_from_this<_Tp, _Lp>; 1481 friend class enable_shared_from_this<_Tp>; 1482 1483 _Tp* _M_ptr; // Contained pointer. 1484 __weak_count<_Lp> _M_refcount; // Reference counter. 1485 }; 1486 1487 // 20.7.2.3.6 weak_ptr specialized algorithms. 1488 template<typename _Tp, _Lock_policy _Lp> 1489 inline void 1490 swap(__weak_ptr<_Tp, _Lp>& __a, __weak_ptr<_Tp, _Lp>& __b) noexcept 1491 { __a.swap(__b); } 1492 1493 template<typename _Tp, typename _Tp1> 1494 struct _Sp_owner_less : public binary_function<_Tp, _Tp, bool> 1495 { 1496 bool 1497 operator()(const _Tp& __lhs, const _Tp& __rhs) const noexcept 1498 { return __lhs.owner_before(__rhs); } 1499 1500 bool 1501 operator()(const _Tp& __lhs, const _Tp1& __rhs) const noexcept 1502 { return __lhs.owner_before(__rhs); } 1503 1504 bool 1505 operator()(const _Tp1& __lhs, const _Tp& __rhs) const noexcept 1506 { return __lhs.owner_before(__rhs); } 1507 }; 1508 1509 template<typename _Tp, _Lock_policy _Lp> 1510 struct owner_less<__shared_ptr<_Tp, _Lp>> 1511 : public _Sp_owner_less<__shared_ptr<_Tp, _Lp>, __weak_ptr<_Tp, _Lp>> 1512 { }; 1513 1514 template<typename _Tp, _Lock_policy _Lp> 1515 struct owner_less<__weak_ptr<_Tp, _Lp>> 1516 : public _Sp_owner_less<__weak_ptr<_Tp, _Lp>, __shared_ptr<_Tp, _Lp>> 1517 { }; 1518 1519 1520 template<typename _Tp, _Lock_policy _Lp> 1521 class __enable_shared_from_this 1522 { 1523 protected: 1524 constexpr __enable_shared_from_this() noexcept { } 1525 1526 __enable_shared_from_this(const __enable_shared_from_this&) noexcept { } 1527 1528 __enable_shared_from_this& 1529 operator=(const __enable_shared_from_this&) noexcept 1530 { return *this; } 1531 1532 ~__enable_shared_from_this() { } 1533 1534 public: 1535 __shared_ptr<_Tp, _Lp> 1536 shared_from_this() 1537 { return __shared_ptr<_Tp, _Lp>(this->_M_weak_this); } 1538 1539 __shared_ptr<const _Tp, _Lp> 1540 shared_from_this() const 1541 { return __shared_ptr<const _Tp, _Lp>(this->_M_weak_this); } 1542 1543 private: 1544 template<typename _Tp1> 1545 void 1546 _M_weak_assign(_Tp1* __p, const __shared_count<_Lp>& __n) const noexcept 1547 { _M_weak_this._M_assign(__p, __n); } 1548 1549 template<_Lock_policy _Lp1, typename _Tp1, typename _Tp2> 1550 friend void 1551 __enable_shared_from_this_helper(const __shared_count<_Lp1>&, 1552 const __enable_shared_from_this<_Tp1, 1553 _Lp1>*, const _Tp2*) noexcept; 1554 1555 mutable __weak_ptr<_Tp, _Lp> _M_weak_this; 1556 }; 1557 1558 template<_Lock_policy _Lp1, typename _Tp1, typename _Tp2> 1559 inline void 1560 __enable_shared_from_this_helper(const __shared_count<_Lp1>& __pn, 1561 const __enable_shared_from_this<_Tp1, 1562 _Lp1>* __pe, 1563 const _Tp2* __px) noexcept 1564 { 1565 if (__pe != nullptr) 1566 __pe->_M_weak_assign(const_cast<_Tp2*>(__px), __pn); 1567 } 1568 1569 template<typename _Tp, _Lock_policy _Lp, typename _Alloc, typename... _Args> 1570 inline __shared_ptr<_Tp, _Lp> 1571 __allocate_shared(const _Alloc& __a, _Args&&... __args) 1572 { 1573 return __shared_ptr<_Tp, _Lp>(_Sp_make_shared_tag(), __a, 1574 std::forward<_Args>(__args)...); 1575 } 1576 1577 template<typename _Tp, _Lock_policy _Lp, typename... _Args> 1578 inline __shared_ptr<_Tp, _Lp> 1579 __make_shared(_Args&&... __args) 1580 { 1581 typedef typename std::remove_const<_Tp>::type _Tp_nc; 1582 return std::__allocate_shared<_Tp, _Lp>(std::allocator<_Tp_nc>(), 1583 std::forward<_Args>(__args)...); 1584 } 1585 1586 /// std::hash specialization for __shared_ptr. 1587 template<typename _Tp, _Lock_policy _Lp> 1588 struct hash<__shared_ptr<_Tp, _Lp>> 1589 : public __hash_base<size_t, __shared_ptr<_Tp, _Lp>> 1590 { 1591 size_t 1592 operator()(const __shared_ptr<_Tp, _Lp>& __s) const noexcept 1593 { return std::hash<_Tp*>()(__s.get()); } 1594 }; 1595 1596 _GLIBCXX_END_NAMESPACE_VERSION 1597 } // namespace 1598 1599 #endif // _SHARED_PTR_BASE_H 1600